Bic, I don't know if you are writing "tongue in cheek", or if you really don't know a lot about Lee Enfields so I will throw out a couple comments on your post.
1st off, of course it was sufficiently tactical to stay in service from the 1890's (Second Boer war) until the 1950's (Post WWII) in England and much later in Dominion countries, in Afghanistan they were used well into the 1980's being the primary rifle used against the Russians until we started supplying large quantities of AK's to supplement those captured.
It was SO tactical that during the WWI battle of Mons, Germans thought they had run into British troops equipped with large numbers of machine guns rather than the rifles they were actually using. (That actually says more for the training of the "Old Contemptibles " I suppose )
2nd, The number painted on the side is of course a "rack number", if you look it over carefully there may be a unit designation stamped some where. I don't recall where the British stamped them, or if all units did so, but I do know that it was a common practice with the colonial Indian Army.
3rd, the sight is not all that optimistic when you remember that it was common to practice "volley firing" where a whole company or platoon would set their sights to a certain elevation and fire at a specific mark that a single shooter would never attempt, and the .303 British, being comparable to the 30-06 or 7.62X 54 was quite capable of doing damage at that range.
Oh, and #4, While the magazine is indeed "detachable", it was not intended as we use them today. The magazine was intended to remain in the rifle being reloaded through the action and only intended to be removed to make cleaning easier.